Heat pump vs gas worked examples
Energy-only comparisons across 6,000–20,000 kWh useful annual heat demand, with electricity, gas and COP sensitivity.
Heat demand is only the starting point
The useful-heat range above lets you see how annual demand changes the comparison, but energy demand alone does not determine whether a heat pump is cheaper to run than a gas boiler. The heat pump's seasonal efficiency, the boiler's real efficiency and the electricity-to-gas price ratio are usually more influential than a single headline COP figure.
A heat pump may achieve different efficiency in mild weather and during cold periods or high flow-temperature operation. Likewise, an older boiler may perform differently from its nominal efficiency. The comparison is therefore best treated as a range rather than a fixed promise.
Separate running cost from installation economics
This calculator focuses on energy cost and break-even assumptions. Installation cost, grants, emitter upgrades, hot-water configuration and maintenance are separate decisions. Use your own annual heat estimate and tariff rates, then test both a conservative and optimistic seasonal efficiency. That makes it easier to see whether the conclusion changes when assumptions move.